KR102472269B1 - Coil coating method - Google Patents

Abstract

The present invention relates to a coil coating method for multi-layer coating of a continuous metal strip (3) located in a strip passing unit, and an electrically insulating primer layer ( 10) Applying and curing the curable polymer varnish 11 for forming the electrically insulating varnish layer 12 on the primer layer 10 using the curable polymer primer 9 for formation and a roller, and curing the primer layer 10 and the varnish layer 12, at least one conductive track 15 having at least electrical conductivity is printed on at least a partial area. In order to improve the reproducibility of the coil coating method, the conductor track 15 is printed in some areas of the pre-cured primer layer 10, and the conductor track 15 and the varnish 11 are wet-on- A coil coating method applied in a wet manner is presented.

Description

Coil coating method

The present invention relates to a coil coating method for multi-layer coating a continuous metal strip disposed in a strip passing unit, wherein a curable polymer primer for forming an electrically insulating primer layer is applied and cured on a flat surface of the metal strip using a roller, , Applying and curing a curable polymer varnish for forming an electrically insulating varnish layer using a roller on the primer layer, and at least one conductor track having electrical conductivity and / or magnetic conductivity between the primer layer and the varnish layer. It relates to a coil coating method for printing on a partial area.

A continuous metal strip coating or coil coating method for multi-layer coating of a continuous metal strip disposed in a strip passing unit is known from the prior art (DE102005061319A1). In this method, after most of the conversion layer is formed on the flat surface of the metal strip, a curable polymer primer is applied and cured to form a primer layer on the flat surface using a roller, and a varnish layer is formed on the primer layer using a roller. A curable polymer varnish is applied and cured. This method also serves to impart functional properties to the metal strip, for example, imparting functional properties such as antistatic properties, electromagnetic properties, antibacterial properties, and electrical properties to the metal strip with a finishing varnish.

As a method for imparting electrical properties to a metal strip by a coil coating method, European Patent EP2605280A1 discloses a method of printing continuous electrical conductor tracks electrically connecting photovoltaic cells between a primer layer and a transparent varnish layer. However, in a subsequent process of processing the metal strip, most of the shape deformation of the metal strip occurs due to molding or the like, which may cause the electrical conductor track to be disconnected, and accordingly, the formation of electrical characteristics may be hindered. Therefore, the known coil coating method cannot reliably and reproducibly impart electrical properties.

Therefore, from the prior art described above, an object of the present invention is to provide a coil coating method capable of imparting electrical and/or magnetic properties to a metal strip reliably and reproducibly. In addition, the coil coating method should be easily applied and can be performed at low cost.

According to the present invention, the above object is achieved by printing a conductor track on a partial area of a pre-cured primer layer and applying the conductor track and varnish in a wet-on-wet manner.

Adhesion of the electrical and/or magnetic conductor tracks on the metal strip can be sufficiently ensured technically and simply by printing the conductor tracks on a partial area on the pre-cured primer layer. Accordingly, the reproducibility of the method of reliably imparting electrical characteristics to the metal strip can be improved. Applying the conductor tracks and the varnish in a wet-on-wet manner can be very effective here, since then the internal stress of the coating layer can be particularly reduced. By means of a wet-on-wet application method, a transition area can be formed between the conductor track and the varnish or connection interface layer, for example in the form of a mixed layer, so that the uniformity of the connection area of the layers can be improved. The transition region may appear between the conductor track and the varnish in an intermediate state in which adhesion is very strong in the metal conductor track. In addition, partial mixing by the applied varnish may be allowed by means of wet-on-wet application on wet conductor tracks or wet dried or pre-cured (but not final cured) conductor tracks. Through this, the edge layer between the above layers is smoothly formed. As a result, mechanical stress, which occurs due to thermal expansion and may appear stronger due to stress concentration in a conductor track with sharp corners or the like, can be reduced in the edge layer. Therefore, unlike the conventional coil coating method, the degree of freedom of internal stress in the final crosslinked state can be improved in the coating layer according to the present invention, and the method can be performed with relatively high reproducibility.

In general, the metal strip may be a steel strip, an aluminum strip or an alloy thereof. These metal strips may be uncoated or coated (organic/metallic), for example galvanized or alloy plated. Also, the metal strip may be a galvanized or alloyed steel strip. It is also generally possible to apply the conductor tracks and varnish wet-on-wet to allow mixing of the conductor tracks and varnish in the edge layer.

In general, a common printing process can be used to print the conductor tracks, for example, a contact printing process such as offset printing, dip printing, etc. or a non-contact printing process such as inkjet printing, screen printing using a template and airbrush can be used. can

The adhesive strength of the conductor track can be improved by pre-curing the applied primer to at least the gelation point. This is because the bonding state of adjacent layers can be improved by avoiding complete curing.

When the primer layer and/or the varnish layer is cured at a substrate temperature in the range of 150 to 300 degrees Celsius through a drying process, a mechanically very strong layer can be obtained.

By pre-curing the primer layer at a substrate temperature in the range of 180 degrees Celsius to 240 degrees Celsius, the gelation point can be surely reached in the crosslinking process, thereby increasing the reproducibility of the method.

The reproducibility of the method is obtained by pre-curing the primer layer and the varnish layer at a substrate temperature in the range of 220 to 260 degrees Celsius. can be further increased.

When the conductor track and the varnish layer are cured together, the internal stress of the coating layer can technically be further reduced. It is preferable that the conductor track and the varnish layer are cured together in the same step so that the degree of freedom of internal stress of the coating layer can be further improved through successive process parameters and the like. In addition, since the single-step coating of the metal strip can be completed at one time, the efficiency of the method can be significantly improved.

When the primer layer and / or varnish layer has a Tg-onset value in the range of 10 degrees Celsius to 75 degrees Celsius in a cured state, the coating process according to the present invention is performed without damage or loss of function through deep drawing or the like. A high degree of deformation of the metal plate can be followed. In addition, the conductor track can be mechanically stabilized through the Tg onset value of the primer layer and/or the varnish layer, and thus the risk of cracking in the electrical conductor track can be reduced. Accordingly, the electrical disconnection phenomenon can be better prevented, and as a result, the reproducibility of the method can be further increased.

In general, a thermomechanical analysis method can be used with a heating rate of 5 K/min at a measurement frequency of 0.1 Hz to determine the Tg onset value.

In the case of a metal strip provided for use in the inner range, it may be sufficient that the Tg onset value of the primer layer is in the range of 10 degrees Celsius to 35 degrees Celsius.

In the case of a metal strip provided for use in an external range, it may be sufficient that the Tg onset value of the primer layer is in the range of 30 degrees Celsius to 75 degrees Celsius. In addition, high corrosion resistance can be provided and the barrier action can be improved through this Tg onset value.

Sufficiently high electrical insulation or electrical dielectric strength can be formed by applying the primer layer with a layer thickness in the range of 3 to 30 μm.

If the electrical conductor tracks are printed with a layer thickness of less than 15 μm, surface non-uniformity of the coating layer and resulting stress cracking can be reduced. Further, when the layer width is smaller than 5 mm, it may be effective to achieve or further enhance the above advantages.

The functionality of the metal strip may be further expanded by printing at least one electrical component electrically connected to the conductor track between the primer layer and the varnish layer. For example, the electrical component may be a transducer.

Conductor tracks can be printed, for example, in a roll-to-roll fashion, technically fast and inexpensive. This roll-to-roll method may be useful when another electrical component is to be provided on the primer layer. For this purpose, for example, using a roller may be effective in increasing the effectiveness of the coil coating method.

It is preferred that the conductor tracks are printed in a repeating pattern in order to increase the reproducibility of the method through a repeating pattern.

The mechanical and chemical resistance of the coating layer can be increased if the primer and varnish are chemically crosslinked.

Before applying the primer, a conversion layer may be formed on the flat surface of the metal strip to form an improved base layer for adhesion of subsequent coating layers. Also, through this, the corrosion resistance of the metal strip can be improved.

However, with the coil coating method according to the invention, it is also possible to coat continuously and (organically and/or metallically) coated metal strips in multiple layers, for example by galvanizing or alloy plating.

The metal strip can be uncoated or (organically/metallicly) coated, for example galvanized or alloy plated.

According to the present invention, the adhesiveness of the electrical and/or magnetic conductor tracks on the metal strip can be sufficiently ensured technically simply by printing the conductor tracks on the pre-cured primer layer in some areas. Accordingly, the reproducibility of the method of reliably imparting electrical characteristics to the metal strip can be improved.

1 is a schematic diagram of an apparatus for a coil coating method.
Fig. 2 is a schematic partial plan view of the coated metal strip according to Fig. 1;
Figure 3 is a cross-sectional view along III-III in Figure 2;
4 is an enlarged cross-sectional view of the region of FIG. 3 .
5 is a schematic second partial plan view of a metal strip coated according to FIG. 1 ;
Fig. 6 is a third schematic partial top view of the metal strip coated according to Fig. 1;

Referring to Figure 1, an apparatus 1 for carrying out the coil coating method according to the present invention is shown. In this device, a continuous metal strip 3, ie a steel strip, is unwound from a coil 30 and a multilayer coating layer 2 is continuously formed on the metal strip in a strip passing unit.

First, the conversion layer 5 is formed on the upper flat surface 4 of the metal strip 3, that is, it is formed on the metallic protective layer 6 of the metal strip 3. Referring to FIG. 1 , the conversion layer 5 is implemented by, for example, applying or spraying and compressing the sol-gel 7 . Thereafter, a primer layer 10 is formed by applying a curable polymer primer 9 to the flat surface 4 using a roller 8 of a coating device (not shown). The primer may be polyester based, for example. Through this, as is known, the adhesion to the metal strip 3 and/or the corrosion resistance of the metal strip 3 is improved.

In FIG. 1, the coating layer of another flat surface 40 of the metal strip 3 in the coil coating method is not shown in detail, but the flat surface 40 is located opposite to the flat surface 4. Although not shown in detail, the coating layer is formed in a similar manner to the flat surface 4, first the conversion layer 5 is applied with sol-gel and then the conversion layer 5 is coated with a finishing varnish. Through this, the flat surface 40 can be protected from flash rust, white rust and environmental influences.

Subsequently, a curable polymer varnish 11, for example, a varnish based on polyester, is applied to the primer layer 10 on the flat surface 4 to form a varnish layer 12. This coating operation is performed in the same way as the primer application process, and is performed using a roller 8 of a coating device (not shown). The applied primer 9 and the applied varnish 11 are cured by dryers 13 and 14, respectively.

To impart electrical properties to the metal strip 3, the primer layer 10 and the varnish layer 12 are electrically insulated. These electrical characteristics are provided by printing electrically conductive conductor tracks 15 in some areas using a roll-to-roll method before applying the varnish 11 . This roll-to-roll method is performed using rollers in the dip printing method. As a paste or ink for forming the conductor track 15, an electrically conductive polymer 16, for example polystyrolsulfonate, is used. Alternatively, the paste or ink may be metal based, for example silver, copper, or gold based, or organic based such as poly-3,4-ethylendioxythiophene (PEDOT) or may be based on graphene. Metal-based inks and/or pastes can exhibit very good conductivity, whereas organic material-based inks and/or pastes can mostly increase corrosion resistance.

The printed conductor tracks 15 described above are then covered with varnish 11 . Thus, as shown in Figs. 2 and 3, a miniature laminate or a miniature coating layer 2 comprising at least partially sealed conductor tracks 15 is formed.

Also, in addition to the conductor track 15 in the coil coating method, another electrical component 17 can be printed as an electrically conductive portion, for example, as shown in FIGS. 2 and 3, two conductive parts. A transducer 18 electrically connected to the sieve track 15 may be printed.

However, unlike the prior art, in the coil coating method according to the present invention, the conductor tracks 15 are printed on the pre-cured and not completely cured primer layer 10, and also the two conductor tracks 15 and the varnish 11 ) is applied in a wet-on-wet manner. This increases the adhesion within the stack of coating layers 2 and also reduces the risk of residual stress in the coating layer, as described in detail below with reference to FIG. 3 .

Referring to the enlarged cross-sectional view of the coating layer 2 shown in FIG. 4 , a transition area 19 surrounding the conductor track 15 , shown as a covering structure, is shown. The transition area 19 is not only formed by heterohesion by intermixing, but is particularly facilitated by wet-on-wet application of ink or paste 16 and varnish 11 in the formation process. By imparting properties to the coating layer 2 more uniformly, internal stress in the coating layer 2 can be surely reduced. Also, the adhesive force between two adjacent layers can be improved. In addition, referring to FIG. 4 , another effect according to the wet-on-wet method can be confirmed. That is, while the edge 20 of the conductor track 15 is formed smoothly, internal notch stress in the edge layer can be prevented. Accordingly, the coating layer 2 according to the present invention is very stable against thermal stress, and as a result, a solid coating layer 2 can be reproducibly manufactured by the coil coating method according to the present invention.

Since the applied primer 9 is pre-cured to at least the gelation point before the conductor track 15 is applied, the short circuit resistance of the coating layer 2 can be further improved. To this end, the primer layer 10 is pre-cured at a substrate temperature in the range of 180 degrees Celsius to 240 degrees Celsius in the dryer 13 . When the thickness of the primer layer was between 3 and 30 μm, it was found to be sufficient for short circuit prevention.

In addition, since the conductor track 15 and the varnish 11 are applied in a wet-on-wet manner and cured in the same step, residual stress in the cured coating layer 2 can be prevented. For this purpose, the dryer 14 is used. are provided With the dryer 14, the primer layer 10 and the varnish layer 12 are finally cured at a substrate temperature in the range of 220 degrees Celsius to 260 degrees Celsius. The coating layer 2 prepared in this way shows a state in which the primer layer 10, the varnish layer 12, and the conductor track 15 are connected to each other. However, although not shown in detail, the metallization layer may be formed in multiple layers by providing between the primer layer 10 and the varnish layer 12 a conductive track 15 having a multilayer structure and which may be electrically insulated from each other. In general, in the case of the conductor track 15 according to the present invention having a layer thickness 24 of less than 15 μm, the effect on the surface of the coating layer is small, and depending on the configuration of the varnish layer 12, it can be visually invisible. . The above effect is ensured by printing the layer width 25 of the conductor track 15 to be less than 5 mm and thus keeping the conductor track 15 narrow. In addition, an opaque varnish layer 12 may be applied to make the conductor track 15 and the electrical component 18 invisible visually. However, in order to improve user convenience, a case where the conductor track 15 is visually visible may also be considered.

The cured primer layer 10 preferably has a Tg onset value in the range of 10 degrees Celsius to 35 degrees Celsius if the metal strip 3 coated with the primer layer or parts belonging thereto are to be used in the inner region. When used in the outer region, the Tg onset value of the cured primer layer 10 is preferably in the range of 30 degrees Celsius to 75 degrees Celsius.

According to FIGS. 5 and 6 a further embodiment of the electrical functionalization of a sheet metal strip 3 is shown in schematic plan view.

Compared to the functionalization embodiment shown in FIG. 2 , another electrical component 17 is shown in the functionalization embodiment according to FIG. 5 . In FIG. 5 instead of transducers 18 two capacitive scanners 21 are printed. The capacitive scanner 21 is connected by means of a conductor track 15 to an electrical contact 22 separated from the varnish layer 12 to form an accessible electrical connection. The structure of the coating layer 2 is the same as that of the embodiment shown in FIG. 3 .

On the other hand, referring to FIG. 6 , a coating layer 102 configured differently from the coating layer 2 is shown. The coating layer 102 differs in that it forms two layers that overlap each other in terms of electrical function and work together for the electrical component 17 . The first layer is formed in the same way as the coating layer 2, and includes a primer layer 10, an electrical conductor track 15 including a sensor surface 23, and a varnish layer 12. As already explained with reference to FIG. 5 , the varnish layer 12 is also separated from the region of the contact surface 22 . After pre-curing the first layer, printing is newly performed on the first layer, and similarly, the conductor track 115, the sensor surface 123, and the varnish layer 112 are wet-on-wet. After coating, the second layer of the coating layer 102 is formed by curing. The sensor surfaces 23 and 123 of the above two layers jointly form a capacitive touch pad as an electric component 17 .

In general, other electrical components 17 other than the electrical conductor tracks 15 and 115 mentioned above may also be applied wet-on-wet using varnish 12 and 112 as well.

Claims (20)

In the coil coating method of coating a continuous metal strip (3) located in a strip passing unit in multiple layers,
A curable polymer primer 9 for forming an electrically insulating primer layer 10 on the flat surface 4 of the metal strip 3 using a roller, and
Applying and curing a curable polymer varnish 11 for forming an electrically insulating varnish layer 12 on the primer layer 10 using a roller,
As a coil coating method of printing at least one conductive track 15 having at least electrical conductivity between the primer layer 10 and the varnish layer 12 on at least a partial area,
The conductor track 15 is printed on a partial area of the pre-cured primer layer 10,
Coil coating method, characterized in that the conductor track (15) and the varnish (11) are applied in a wet-on-wet manner. 2. Coil coating method according to claim 1, characterized in that the applied primer (9) is pre-cured at least to its gelation point. The coil coating method according to claim 1, characterized in that the primer layer (10) and/or the varnish layer (12) is cured at a substrate temperature in the range of 150 to 300 degrees Celsius by a drying process. 4. Coil coating according to claim 3, characterized in that the applied primer (9) is pre-cured at least to its gelation point, and the primer layer (10) is pre-cured at a substrate temperature in the range from 180 to 240 degrees Celsius. Way. 4. Coil coating method according to claim 3, characterized in that the primer layer (10) and the varnish layer (12) are finally cured at a substrate temperature in the range of 220 to 260 degrees Celsius. 2. Coil coating method according to claim 1, characterized in that the conductor track (15) and the varnish layer (12) are cured together. 7. Coil coating method according to claim 6, characterized in that the conductor track (15) and the varnish layer (12) are cured together in the same step. The coil coating method according to claim 1, characterized in that the primer layer (10) and/or varnish layer (12) has a Tg onset value in the range of 10 degrees Celsius to 75 degrees Celsius in a cured state. . 9. Coil coating method according to claim 8, characterized in that the metal strip (3) in the inner range of the Tg onset value of the primer layer (10) is in the range of 10 degrees Celsius to 35 degrees Celsius. 10. Coil coating method according to claim 9, characterized in that the metal strip (3) in the outer range of the Tg onset value of the primer layer (10) is in the range of 30 to 75 degrees Celsius. The coil coating method according to claim 1, characterized in that a primer layer (10) having a layer thickness of 3 to 30 μm is applied. 2. Method according to claim 1, characterized in that the electrical conductor tracks (15) are printed with a layer thickness (24) of less than 15 μm and/or a layer width (25) of less than 5 mm. The coil coating method according to claim 1, characterized in that between the primer layer (10) and the varnish layer (12) at least one electrical component (17) electrically connected to the conductor track (15) is printed. . 14. Method according to claim 13, characterized in that the transducer (18) is printed as the electrical component (17). 2. Method according to claim 1, characterized in that the electrical conductor tracks (15) are printed in a roll-to-roll manner. 16. Method according to claim 15, characterized in that the electrical conductor tracks (15) are printed using a roller. 2. Method according to claim 1, characterized in that the conductor tracks (15) are printed in a repeating pattern. 2. Coil coating method according to claim 1, characterized in that the primer (9) and the varnish (11) are chemically crosslinked. 2. Method according to claim 1, characterized in that a conversion layer (5) is formed on the flat side (4) of the metal strip (3) before applying the primer (9). 2. Method according to claim 1, characterized in that the continuous and coated metal strip (3) is coated in multiple layers.

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